Electromagnetic winding having coil wrapper with window insulating flaps



PFE 16, 1968E A. J. LIBERMAN v 3,378,800

LECTROMAGNETIC WINDING HAVING COIL WRAPPER WITH WINDOW INSULATING FLAPSl 5 Sheets-Sheet l Filed, Jan. 25 1967 JMW@ April 16, 1968 A. J.LIBERMAN 3,378,300

` ELECTROMAGNETIC WINDING HAVING COIL WRAPPER WITH WINDOW NSULATINGFLAPS 5 Sheets-Sheet L,

Filed Jan. 25, 1967 April 16, 1968 A. J. LIBERMAN 3,378,800

ELECTROMAGNETIC WINDING HAVING COIL WRAPPER WITH WINDOW INSULATING FLAPSFiled Jan. 25, 1967 Sheets-Sheet ."5

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United States Patent O 3,378,800 ELECTROMAGNETIC WINDING HAVING Cil..WRAPPER WITH WINDOW INSULA'IlNG FLAPS Arnold J. Liberman, Skokie, Ill.,assignor, by mesne assignments, to Electric Products Manufacturing Co.,Beliwood, Ill., a corporation of Delaware Filed Jan. 25, 1967, Ser. No.611,595 10 Claims. (Cl. 336-192) ABSTRACT F THE BESCLGSURE Acircumferential wrapper for a transformer cc-il has aps extending fromits side edges. The flaps are tucked into the coil window to insulatesame. Tabs on the flaps provide complete coverage of all four innerfaces of the Window. Extended portions of the tabs protect those of theinner coil edges which are not overlain by the flaps.

- Specification This invention relates to an improved coil wrapper foruse lwith transformer or reactor coils and is particularly suitable forcoils having an axial length greater than the Window width, and relatesto the winding or wrapped coil itself.

Transformer and reactor coils are mounted on square or rectangular corelegs; hence they are Wound with a square or rectangular window toreceive the core leg. The innermost convolutions of the coil must beinsulated from the core. Sometimes this is accomplished by winding thecoil on a tube of cardboard or other insulating materail having a squareor rectangular cross section. In other instances, a tube lof cardboardor other insulating material may be inserted after the coil is wound.

It has been proposed in Goad Patent No. 1,797,768 and Henderson PatentNo. 2,749,525 to provide a wrapper which overlies the end face of thecoil, and instead of cutting a square opening which overlies the coilWindow, to make cuts in such a 4manner that iiaps will be provided whichcan extend into the Window for insulating purposes. However, 'theseproposals have been made for fiat coils, and the arrangement sho-wn isnot sui-table for a coil where the length is equal to or greater thanthe window width. Furthermore, the arrangement does not provide awrapper for all four outer faces of the coil, that is, it does notprovide a circumferential wrapper.

According to my invention, I provide a wrapper for the four outer facesof the coil which is in the form of an elongate member of insulatingmaterial, such as coated paper stock having a length somewhat greaterthan the circumference of the coil. Then along each side edge of theelongate member I provide two tiaps which can be folded inwardly intothe window to provide the window insulation. The flaps have tabs whichinsulate adjacent inner faces of the window. By thus providing the iiapsalong the edge of a circumferential wrapper, the wrapper design is notas limited as in former arrangements, and in particular I provide with asingle blank both a circumferential wrapper and Window insulation forall four inner faces.

My invention provides other advantages in that portions of the end facesof the coil are also covered, and the inner coil edge of the uncoveredportions are protected by iiap extensions which project beyond the endfaces.

Also, according to my invention, the wrapper may also serve as aterminal mount or boar-d.

Other objects, features, and adavntages will become apparent as thedescription proceeds.

With reference now to the drawings in which like reference numeralsdesignate like parts:

ICS

FIG. l is an end View of a coil embodying my invention;

FIG. 2 is a side View;

FIG. 3 is atop view;

FIG. 4 is a vertical section taken along line 4-4 of FIG. 3;

FIG. 5 is a plan section taken along line 5-5 of FIG. l;

FIG. 6 is a perspective view of a partially folded wrapper illustratingthe operation;

IFIG. 7 is a plan View of the unfolded wrapper or blank;

FIG. 8 is a plan View of a modified Wrapper;

FIG. 9 is a section taken along line 9-9 of FIG. 8;

FIG. l0 is a perspective view of an unwrapped coil;

FIG. ll is a plan view similar to FIG. 5, but of an unwrapped coil;

FIG. 12 is a view similar to FIG. 7, but showing a modified arrangement;

FIGS. 10 and ll show an unwrapped coil 10 having Ithe axial length Lmade up of layers 11 of wire or alternate layers of wire and paper. Thecoil has a rsquare or rectangular window 12 of width W. As shown in FIG.l, the shape of the coil is maintained during handling by a strip ofadhesive tape 13 which surrounds one portion.

As shown in FIG. l0, lthe coil has four outer vfaces 14, four innerfaces 15a, 15b, 15C, 15d, and end faces 16. The end lface 16 can beconsidered as being made up of four rectangular portions, 16a, 16b, 16e,16d, plus corner portions 17. Where the end face intersects the innerfaces, the inner edge is designated by the reference numeral 18. Thewire convolution which occupies the inner edge position is particularlyvulnerable to nicking in the course of handling, and inserting the coreleg. Therefore, in addition to providing insulation `for the inner faces15, it is desirable to provide some mechanical protection for the inneredge 1S.

As shown in FIG. 7, the wrapper or blank 20 comprises an elongate bodyportion 21 and four fiaps 22, two flaps being located along each sideedge of the elongate portion 21. The liaps 22 are connected to the bodyportion by connecting portions 23. Each flap is divided into threeparts, comprising a rnid part 24 and tabs 25. Score lines 26- areprovided to facilitate folding.

As shown in FIGS. l to 4i, the elongate body portion 21 is wrappedaround and overlies all four outer faces I4, and is secured in place bya strip of adhesive tape 27.

The flaps are then folded downwardly and inwardly into the window 12 sothat the connecting portions 23 overlie the end faces lob and 16d. Themid parts 24 of the flaps overlie inner faces 15b and 15d, and the "tabs25 overlie inner faces 15a and 15C.

The tab edges 25 may be rounded sufficiently to facilitate entrance intothe window 12. The longitudinal dimension X of the mid part 24 (i.e. thedimension running longitudinally of the blank 20) is substantially thesame as the width W of the window 12. The transverse dirnension Y of themid part 24 is more than half the axial length of the coil. As shown inFIG. 1l, the inner face 15 may be divided into two end halves 28, andeach end half may be considered as being made up of two end quarters 29.Thus it will be seen that the dimensions are such that the mid part 24will completely overlie an end half 28, and the opposite mid part willcompletely overlie the other end half 28, and there will be someoverlapping so that the inner face 15 is completely covered by the twomid parts 24, as shown in FIG. 5.

Each tab 25 overlies ya complete end quarter, as shown in FIG. 5. Thusin the case of end face 15a, it will be completely covered by the fourtabs which overlap each other.

As shown in FIG. 7, there are L-shaped cuts so that the connectingportion 23 will be of a greater width than the mid part 24. Theadvantage of this arrangement is that the connecting portion 23, asshown in FIG. 1, extends partially into the corner portions 17 of thewinding, giving greater protection to the end face of the coil. Also, aportion 31 of the tabs 25 extend axially from the coil as shown in FIGS.2 and 3, and thus provide mechanical protection for the inner edges 18band 18d, the inner edges 18a and 18C being protected by the overlyingconnecting portions 23.

Thus, mechanical protection is provided for all four of the inner edges18.

The extended portions 31 may also serve as spacer members to spaceadjacent coils from each other by a predetermined distance. This coilspacing is necessary in the case of leakage reactance transformers andballasts for fluorescent lamps and other gaseous discharge devices.

Instead of having the aps 22 located opposite to each other as shown inFIG. 7, it is possible to stagger them as shown in FIG. 12 so that thereis one mid part for each inner face 15. Here the different mid parts aredesignated by the letters A, B, C and D, corresponding to the innerfaces overlain by each. One end half of each inner face 15| is coveredby a mid part 24, and the other end is covered by the two tabs 25. InFIG. 7, the oppositely disposed mid parts completely overlie the faces15b and 15d, whereas the inner faces 15a1 and 15C are completely coveredby the inner tabs as shown in FIG. 5.

A further modification is shown in FIGS. 8 and 9 in which the end part32 of the elongate body portion 21 which overlaps the other end, hasstapled to it by staplesl 33 two insulated coil leads 34. The coil ends35, as shown in FIGS. 1 and 2, may thus be soldered to the bared ends ofthe insulated leads 34, the wrapper part 32 thus serving as a terminalboard which provides the desired strain relief for the coil leads A34.

A particularly suitable material for the wrapper is a non woven nylonlibrous product sold under the Du Pont trademark Nomex.

Although preferred embodiments of the present invention have beendescribed herein, it will be understood that various modifications andchanges may be made in the construction shown without departing from thescope of the invention as pointed out in the appended claims.

I claim:

1. An electromagnetic winding comprising a coil having four outer faces,a window providing four inner faces, and two end faces each having fourrectangular portions and-four corner portions, and a wrapper for saidcoil, wherein said wrapper comprises an elongate body portion overlyingsaid four outer faces, said elongate body portion having two flapsextending from each side thereof, each flap having a mid portionoverlying the end half of one inner face and two tabs overlying theadjacent end quarters of adjacent inner faces, and a connecting portiondisposed between each flap and said elongate body portion and overlyingone of said four rectangular portions of said end face.

2. An electromagnetic winding as claimed in claim 1 in which each tabhas a portion extending outwardly of said window beyond said end face.

3. An electromagnetic Winding as claimed in claim 1 in which saidconnecting portion has a dimension greater than the width of said windowto cover at least a portion of one of said corner portions of said endface.

4. An electromagnetic winding as claimed in claim 1 in which each tabhas a portion extending outwardly of said window beyond said end face,said connecting portion having a dimension greater than the width ofsaid window to cover at least a part of one of said corner portions ofsaid end face.

5. An electromagnetic winding as claimed in claim 1 in which saidelongate body portion has a rst end and a second end, said iirst endoverlapping said second end, means securing said iirst end to saidsecond end in overlapping relationship, coil leads overlapping saidfirst end, means securing said coil leads to said rst end, said coilhaving coil ends electrically connected with said coil leads, wherebysaid first end portion serves as a terminal board for said winding.

6. An electromagnetic winding as claimed in claim 1 in which said coilhas an axial length greater than the width of said window.

7. An electromagnetic winding as claimed in claim 1 in which said flapsare oppositely disposed from each other, two of said oppositely disposedflaps overlying the same inner face.

8. An electromagnetic winding as claimed in claim 1 in which said apsare staggered with respect to each other, each flap overlying adifferent inner face.

9. A circumferential coil wrapper for a coil having a window providingfour inner faces, and two end faces, wherein the improvement comprises ablank having an elongate body portion and two aps extending from eachside thereof, each llap having a mid portion adapted to overlie the endhalf of one inner face and two tabs adapted to overlie the adjacent endquarters of adjacent inner faces, and a connecting portion disposedbetween each ap and said elongate body portion adapted to overlie aportion of an end face, said connecting portion being separated fromsaid body portion and from said flap by fold lines, and said mid portionbeing separated from said tabs by fold lines.

10. A circumferential coil wrapper for a coil having a window providingfour inner faces, and two end faces, whereinl the improvement comprisesa blank having an elongate body portion and two aps extending from eachside thereof, each iiap having a mid portion adapted to overlie the endhalf of one inner face and two tabs adapted to overlie the adjacent endquarters of adjacent inner faces, and a connecting portion disposedbetween each flap and said elongate body portion adapted to overlie aportion of an end face, the transverse dimension of each tab beinggreater than the transverse dimension of said mid part, and an L-shapedslit separating adjacent portions of a tab and a connecting portionReferences Cited UNITED STATES PATENTS 1,052,303 2/ 1913 Aven 336--208XR 2,875,420 2/1959 Hofer et al 336-209 XR 3,317,875 5/ 1967 Williams336-198 DARRELL L. CLAY, Primary Examiner. T. J. KOZMA, AssistantExaminer.

